DE102020121303A1 - Device and method for coating a panel-shaped workpiece - Google Patents

Abstract

Device (1) for coating a panel-shaped workpiece (2) which has at least one narrow surface (4) and at least one wide surface (6) and preferably consists at least in sections of wood, derived timber product, plastic or the like, in the area of a wide surface (6), comprising a coating unit (10) for coating the workpiece (2), which has a pressing element (12) for pressing a coating material (8) onto the workpiece (2), and a displacement unit (20) for bringing about a relative movement between the pressing element (12 ) and the workpiece. The device (1) has a feed unit (30) for feeding a band-shaped adhesive (40) which is used to create an adhesive bond between the coating material (8) and the workpiece (2).

Description

technical field

The invention relates to a device for coating a panel-shaped workpiece which has at least one narrow surface and at least one wide surface and preferably consists at least in sections of wood, derived timber product, plastic or the like in the area of a wide surface, according to the preamble of patent claim 1.

State of the art

In the furniture and component industry, panel-shaped workpieces are often provided with a decorative coating, such as decorative paper, in the area of the broad surface. For this purpose, laminating systems are used, such as those in EP 2 433 769 A1 are revealed.

According to this, there are initially methods in which coating material webs are first coated with adhesive outside of a laminating plant in order to activate the adhesive at a later point in time and to attach the coating material web to a workpiece. However, this requires large pre-coating plants and there are restrictions on the conveyance of pre-coated coating material webs. In addition, the EP 2 433 769 A1 Problems from an energetic and environmental point of view.

Hence the beats EP 2 433 769 A1 proposes applying the adhesive to the workpiece at a suitable point and in a suitable quantity during the feeding of the coating material web to the workpiece. In principle, this technology has proven itself. However, it has been shown that there is a need to achieve an even smoother or evener surface of the workpieces.

Presentation of the invention

The invention is based on the object of providing a device and a method of the type mentioned at the outset, which enable the coated workpieces to have a particularly smooth and even surface.

According to the invention, this object is achieved by a device according to claim 1 and a method according to claim 13 . Particularly preferred developments of the invention are specified in the dependent claims.

The invention is based on the idea of increasing the smoothness and evenness of the entire coating by means of a particularly defined and uniform layer of adhesive. For this purpose, it is provided according to the invention that the device has a feed unit for feeding in a band-shaped adhesive agent, which is used to create an adhesive connection between the coating material and the workpiece.

The use of a band-shaped adhesive or a corresponding feed unit results in a very defined and uniform application quantity and adhesion of the adhesive. This was not possible to the same extent with previous systems, which applied the adhesive in the machine, for example by means of a nozzle or roller, and often involved a great deal of effort. The tape-shaped adhesive according to the invention thus makes a significant contribution to increasing the smoothness and evenness of the entire coating. In addition, the cleaning effort is minimized.

According to a development of the invention, it is provided that the feed unit has a stretching unit for stretching the band-shaped adhesive in a direction transverse to the feed direction. In this way it is ensured that the strip-shaped adhesive is supplied to the surface of the workpiece to be coated with as little folds, unevenness or warping as possible. This further increases the smoothness and evenness of the entire coating.

Within the scope of the present invention, the stretching unit can be configured in a variety of ways. The stretching unit preferably has at least one spreader roller. This results in effective and rapid stretching of the tape-shaped adhesive with a simple construction of the overall device. It is particularly preferred that at least one spreader roller is arranged in such a way that the wrap angle of the band-shaped adhesive is at least 45°, preferably at least 60°. The inventors have found an effective stretching effect for these angular ranges without the specifications for the construction of the overall device having to be restricted too narrowly.

In the context of the present invention, the band-shaped adhesive can in principle be fed directly into the joint gap between the workpiece and the coating material. According to a development of the invention, however, it is provided that the device has an adhesion unit for adhering the band-shaped adhesive to the workpiece or the coating material. As a result, the band-shaped adhesive can be adhered to one of the two joining partners in a particularly precise, targeted and trouble-free manner, which makes a further contribution to the evenness and smoothness of the entire coating.

It is particularly preferred that the adhesion unit has at least one calender roller for pressing the band-shaped adhesive onto the workpiece and/or the coating material. In this way, on the one hand, a smoothing effect of the band-shaped adhesive can be achieved, and on the other hand, any unevenness in the workpiece itself can be at least partially evened out by the band-shaped adhesive penetrating into any bumps and the total surface of the band-shaped adhesive being leveled by the at least one calender roller.

It is particularly preferred here that the surface of the at least one calender roll has an average peak-to-valley height Rz of at most 4 μm, preferably at most 2 μm. This results in a particularly pronounced smoothing effect, which has a positive effect on the evenness and smoothness of the overall coating. A corresponding contribution to evenness and smoothness is also obtained if at least one calender roll has a concentricity of at most 0.1 mm and/or an angular accuracy of at most 0.05. It is also preferred that the surface is hard chrome plated at least in sections. As a result, the smoothness and flatness can be stably secured, and adhesion of the tape-shaped adhesive or a base material to the calender roll is avoided.

In addition, according to a development of the invention, it is provided that the adhesion unit has at least one application unit, in particular application roller, for applying the strip-shaped adhesive to the workpiece and/or the coating material. Since the band-shaped adhesive is initially only applied (and not finally fixed) by the application unit, there is still scope for further optimization or smoothing of the band-shaped adhesive, for example using the calender roller already mentioned above or other means. At the same time, the application ensures that the band-shaped adhesive is already in the correct position and, if possible, no longer creases or forms bumps. Overall, the feed unit therefore makes a further contribution to increasing the smoothness and evenness of the entire coating.

According to a development of the invention, it is also provided that the adhesion unit has at least one activation unit, in particular an energy source, for at least partially activating the band-shaped adhesive. As a result, the band-shaped adhesive can already be adhered to the workpiece or the coating material at least to a certain extent in the adhering unit, whereby the smooth and wrinkle-free state of the band-shaped adhesive can be fixed. In addition, the strip-shaped adhesive can also be smoothed better after at least partial activation, for example to compensate for unevenness in the workpiece. Furthermore, the at least partial activation in the area of the feed unit makes it possible for a final activation in the area or shortly in front of the coating unit to require only a small amount of energy or, under certain circumstances, no energy input at all.

Various energy sources can be used in the activation unit within the scope of the invention, such as in particular hot air sources, laser sources, infrared sources, ultrasound sources, microwave sources and combinations thereof.

It is particularly preferred that the energy source is set up to act on the band-shaped adhesive after the application unit and preferably before the at least one calender roller. As already outlined above, this enables a multi-stage process in which the band-shaped adhesive is first pre-positioned and applied in the desired and precise position using the application unit, in order to then activate the band-shaped adhesive using the energy source so that it is attached to the adhere to the workpiece or the coating material and can be smoothed more easily. Finally, at least one calender roller ensures that the band-shaped adhesive is reliably pre-fixed and that the band-shaped adhesive is smoothed and leveled to a high quality. As a result, this leads to an overall coating that has a very high degree of smoothness and flatness and at the same time is reliably adhered to the workpiece.

According to a development of the invention, it is provided that the device is provided with a removal unit for removing an adhesive carrier material that has passed through the adhesion unit. This enables a joining concept in which the band-shaped adhesive is first stored and supplied on a suitable carrier material, and the adhesive carrier material can then be removed and disposed of. This further enhances the smoothness and flatness of the overall coating because the adhesive tape is protected and held stable by the adhesive backing material, reducing the likelihood of damage, wrinkles, or other non-uniformities. In addition, the tape-shaped adhesive is also less likely to be damaged during peeling (e.g. from a roll), for example because it adheres to adjacent layers of the rolled-up tape-shaped adhesive. This also further increases the smoothness and evenness of the overall coating.

It is particularly preferred that the adhesive carrier material has a higher tensile strength than the tape-shaped adhesive. As a result, the adhesive carrier material has a further protective function, so that the band-shaped adhesive is not overstretched or damaged, for example during the conveying or stretching process.

Although the device according to the invention can be used with a wide variety of coating materials, the advantages according to the invention are particularly pronounced when the coating material has a thickness of at most 0.5 mm. Because it is precisely with such thin coating materials that it is of decisive importance for the smoothness and evenness of the overall coating that the adhesive layer is also particularly smooth and even and possibly even leveling, as is the case with the present invention.

The advantages mentioned above are particularly pronounced in a method according to one of claims 13 and 14.

character list

• 1 shows schematically a side view of a first embodiment of the device according to the invention;
• 2 shows schematically a side view of a second embodiment of the device according to the invention.

Detailed Description of Preferred Embodiments

Preferred embodiments of the invention are described in detail below with reference to the accompanying drawings.

In the device 1 for coating a plate-shaped workpiece 2 according to a first embodiment of the invention 1 shown schematically in a side view. The device 1 is used for coating workpieces 2, which in the present embodiment consist, for example, of wood, derived timber product, plastic or the like, such as are widely used in the furniture and component industry. These are plate-shaped workpieces 2 which accordingly have several narrow surfaces 4 and usually two wide surfaces 6 . Examples include doors, table tops, etc.

In the area of the narrow surface 4, such workpieces 2 are often coated with so-called edges. In the area of the broad surface 6, on the other hand, a different type of coating material 8 is often used, which often has a small thickness of, for example, only 0.3 mm and is available in large (continuous) rolls or as sheets (i.e. with a limited length, for example in the order of of the workpieces to be coated) is provided, which can have a width of one meter or more, for example. The workpieces 2 (in a direction perpendicular to the plane of the drawing in 1 ) own. The coating material can consist, for example, of printed paper impregnated with suitable resins.

In the 1 The first embodiment shown is designed as a so-called continuous system, in which the workpieces 2 are placed on a traversing unit 20 in the form of a roller conveyor in a continuous direction (from left to right in 1 ) are funded. Instead of a roller conveyor, a variety of other traversing units can also be used, such as conveyor belts, conveyor chains, conveyor tables, etc. It should also be noted that the present invention can also be used on so-called stationary machines, in which the workpieces 2 are essentially stationary during the coating process and the required units of the device are moved in relation to the workpiece 2 to be coated. Mixed forms of both concepts are also possible within the scope of the invention.

As in 1 As can be seen, the device 1 comprises a coating unit 10 which is used to apply the coating material 8 to the broad surface 6 of the workpiece 2 . For this purpose, the coating unit 10 comprises a pressure element 12, which is formed as a pressure roller (calender roller) 12 in the present embodiment. The pressure roller 12 can be heated by an energy source 14 so that a band-shaped adhesive 40, which in the present embodiment has already been applied to the broad surface 6 of the workpiece 2 to be coated, can be indirectly heated and thus activated (made adhesive).

Upstream of the coating unit 10 there is a feed unit 30 for feeding the strip-shaped adhesive 40, which is provided in the form of a roll, for example, and is fed by the feed unit 30 to the surface 6 of the workpiece to be coated. Alternatively, the band-shaped adhesive 40 can also be provided as sheet goods, ie in the form of individual web sections whose length is, for example, of the order of magnitude of the length of the workpieces to be coated. The tape-shaped adhesive can be, for example, a hot-melt adhesive material, optionally with different other fabrics or carrier materials can be combined. Various other adhesives can also be used within the scope of the invention.

In order to ensure a crease-free and level feeding of the band-shaped adhesive, the feeding unit 30 in the present embodiment has a stretching unit, which is designed as a so-called spreader roller 32 in the present embodiment. The spreader roller 32 causes the band-shaped adhesive 40 to be stretched in a direction transverse to the feed direction, ie in a direction perpendicular to the plane of the drawing in FIG 1 . For this purpose, the spreader roller can, for example, have suitable surface elements which ensure that the band-shaped adhesive agent passing the outer peripheral surface of the roller 54 is stretched. Alternatively or additionally, the longitudinal axis of the spreader roller (perpendicular to the plane of the drawing in 1 ) be curved, which together with a corresponding curvature of the outer peripheral surface leads to a stretching effect. Other constructive solutions are also possible.

The angle of wrap of the band-shaped adhesive is 40, as in 1 as can be seen, in the present embodiment approximately 60°, with larger or somewhat smaller angles also being advantageously possible within the scope of the invention. This ensures that a continuous and gentle but also reliable stretching process is carried out, which leads to a smooth and even layer of adhesive on the workpiece 2 .

In the present embodiment, the feed unit 30 is followed by an adhesion unit 50 which serves to adhere the band-shaped adhesive 40 to the broad surface 6 of the workpiece 2 to be coated. For this purpose, the adhesion unit 50 in the present embodiment comprises a contact roller 54, an activation unit 56 and two calender rollers 52. The activation unit 56 is located here, as in FIG 1 as can be seen, between the feed roller 54 and the calender rollers 52. Consequently, the band-shaped adhesive is first applied to the broad surface 6 of the workpiece 2 to be coated by means of the feed roller 54, then activated (made adhesive) by means of the activation unit 56 and finally by means of the calender rollers the broad surface 6 of the workpiece 2 to be coated is pressed and thereby smoothed.

In the present embodiment, the activation unit 56 has an energy source in the form of a hot air blower, which blows hot air at a temperature of approximately 150° C. to 450° C. and an overpressure onto the band-shaped adhesive 40 in order to activate it. The excess pressure can come from a blower or from a compressed air source that provides a pressure of at least 1.5 bar, for example. Alternatively or additionally, however, other types of energy sources can also be used, such as laser sources, infrared sources, ultrasound sources, microwave sources and combinations thereof.

In the present embodiment, the calender rolls 52 have a hard chrome-plated surface with an average peak-to-valley height Rz of approximately 1 μm. The concentricity of the calender rolls is 0.1mm or less, and the angular accuracy of the calender rolls is 0.05 or less. The angular accuracy is the deviation of the roller axis relative to the orthogonal to the feed direction of the band-shaped adhesive 40. Overall, this achieves excellent smoothing of the band-shaped adhesive 40 applied to the broad surface 6.

A second preferred embodiment of the device 1 according to the invention is in 2 shown schematically in a side view. The second embodiment differs from the first embodiment in that the band-shaped adhesive 40 is provided on an adhesive carrier material, such as a carrier foil, a carrier fabric, etc. In addition, the device 1 in the second embodiment comprises a removal unit 60 for removing the adhesive carrier material 42 which has passed through the adhesion unit 50.

As in 2 can be seen, the adhesive carrier material 42 thus remains connected to the band-shaped adhesive 40 up to the last calender roller 52 and is then removed by means of the removal unit 60 (e.g. rolled up), while the band-shaped adhesive 40 remains on the broad surface 6 of the workpiece 2 to be coated . However, it should be noted that the adhesive carrier material can also be removed elsewhere, for example upstream of the calender rolls 52.

QUOTES INCLUDED IN DESCRIPTION

This list of the documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 2433769 A1 [0002, 0003, 0004]

Claims (14)

Device (1) for coating a panel-shaped workpiece (2) which has at least one narrow surface (4) and at least one wide surface (6) and preferably consists at least in sections of wood, derived timber product, plastic or the like, in the area of a wide surface (6), comprising: a coating unit (10) for coating the workpiece (2), which has a pressing element (12) for pressing a coating material (8) onto the workpiece (2), and a displacement unit (20) for bringing about a relative movement between the pressing element ( 12) and the workpiece, characterized in that the device (1) has a feed unit (30) for feeding a band-shaped adhesive (40) which is used to create an adhesive bond between the coating material (8) and the workpiece (2). device after claim 1 wherein the feeding unit (30) comprises a stretching unit (32) for stretching the band-shaped adhesive (40) in a direction transverse to the feeding direction. device after claim 2 , in which the stretching unit (32) has at least one spreader roller. device after claim 3 , in which at least one spreader roller (32) is arranged in such a way that the wrap angle of the band-shaped adhesive (40) is at least 45°, preferably at least 60°. Device according to one of the preceding claims, in which an adhering unit (50) for adhering the band-shaped adhesive (40) to the workpiece (2) and/or the coating material (8) is provided. device after claim 5 , in which the adhesion unit (50) has at least one calender roller (52) for pressing the band-shaped adhesive (40) onto the workpiece (2) and/or the coating material (8), which preferably has at least one of the following properties: Average peak-to-valley height Rz of the surface of at most 4 µm, preferably at most 2 µm; • Surface hard-chromed, at least in sections; • run-out accuracy of 0.1 mm or less; • Angular accuracy of 0.05 or less. device after claim 5 or 6 , in which the adhesion unit (50) has at least one application unit (54), in particular application roller, for applying the strip-shaped adhesive (40) to the workpiece (2) and/or the coating material (8). Device according to one of Claims 5 until 7 , in which the adhesion unit (50) has at least one activation unit (56), in particular an energy source, for at least partially activating the band-shaped adhesive (40), which is preferably selected from hot air sources, laser sources, infrared sources, ultrasonic sources, microwave sources and combinations thereof. device after claim 8 , in which the energy source (56) is set up to act on the band-shaped adhesive (40) after the application unit (54) and preferably before the at least one calender roller (52). Apparatus according to any one of the preceding claims, wherein a discharge unit (60) for discharging an adhesive carrier material (42) which has passed through the adhesion unit (50) is provided. device after claim 10 wherein the adhesive backing material (42) has a higher tensile strength than the tape-shaped adhesive (40). Apparatus according to any one of the preceding claims, wherein the coating material has a thickness of at most 0.5mm. Method for coating a panel-shaped workpiece (2) which has at least one narrow surface (4) and at least one wide surface (6) and preferably consists at least in sections of wood, wood-based materials, plastic or the like, using a device (1) according to one of the preceding ones Claims, with the steps: Bringing about a relative movement between the pressing element (12) and the workpiece (2) by means of the traversing unit (20), supplying a band-shaped adhesive (40) to a broad surface (6) of the workpiece (2) by means of the supply unit (30), and Coating of the broad surface (6) of the workpiece (2) with the coating material (8) by means of the coating unit (10), the tape-shaped adhesive (40) serving to create an adhesive connection between the coating material (8) and the workpiece (2). procedure after Claim 13 , in which the broad surface (6) has a width of at least 50 cm, measured in a direction transverse to Rich means of feeding the tape-shaped adhesive (40).

Images